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LAMINITIS

Written By: Dr. Alberto Rullan

Basic review of lamintis: Part 1 – Anatomy and diagnosis

Laminitis is one of the most painful diseases affecting the horse’s feet. This disease may affect any horse at any stage of their life and training career, although some breeds appear to be more prone to it. This article gives the horse owner some basic knowledge about this disease including tips on identifying it, and general diagnostic and treatment options that the veterinarian-farrier team may perform.

The term laminitis means that there is inflammation in the lamina of the foot. The lamina is the tissue that connects the hoof to the coffin bone (also known as third phalanx or P3). The bone stays in place within the hoof capsule due to a “velcro” type of interdigitation of the tissues. This connection is very strong and only under certain circumstances can fail, sometimes resulting in laminitis.

Having a general knowledge of the anatomy is very important in order to better understand any disease of the equine foot. These two pictures (a photo and radiograph of the foot) give the reader a basic anatomical orientation of the horse’s foot.

Pic_1_and_Pic_2_Horse_foot.JPG

Laminitis is usually categorized as acute or chronic. For simplicity purposes we will define acute laminitis as when the disease has recently happened. At this stage, laminitis is accompanied by lameness before the appearance of external changes in hoof conformation. Chronic laminitis is when the disease has been going on for some time (ie weeks or months). In chronic laminitis changes in the hoof conformation are present.

Signs of acute laminitis include the following:

· Lameness, in a straight line.

o This can vary from severe to mild signs. A mild episode can manifest by a “choppy” short gait. When a horse is turning in circles it shows a difficult, slow turn, putting more weight in the hind limbs. A severe episode can manifest as reluctant to move or even recumbency (laying down).

· Shifting weight when standing.

· Heat around the coronary band and wall of the hoof

· Increased digital pulse in the feet. This can be palpated by placing the index finger at the level of the back of the fetlock where the vessels run down to the feet.

· Pain in the toe region when pressure is applied with hoof testers

· A “sawhorse stance,” as shown in the picture, with the front feet stretched out in front in order to alleviate pressure on the toes and the hind feet under the body.

Laminitic Stance

Signs of chronic laminitis may include the following:

• Rings around the hoof wall that become wider as they are followed from toe to heel

• Bruised soles that can be seen when the hoof sole is being trimmed

• Widened white line, commonly called “seedy toe,” with occurrence of blood pockets and/or abscesses

• Dropped soles or flat feet

• Dished hooves, which is the result of unequal rates of hoof growth

Nowadays, one of the most important diagnostic tools for evaluating laminitis is radiography.

Below are examples of the basic three radiographic views that should be evaluated in a laminitic horse. The notable changes are the loose of parallelism of the coffin bone with respect to the dorsal hoof wall on the lateral view. This is what we call rotation of the coffin bone, deterioration of the solar margin of the coffin bone on the dorso ventral (DV) view and medial-lateral unbalance on the anterior posterior (AP) view.

The veterinarian can take several measurements in order to have an idea of the severity of the disease process and as a base line evaluation to compare with future radiographs.

X-ray of horses feet

Venogram as diagnostic aid tool

Venography is a good technique in order to provide diagnosis and prognosis for a laminitic horse. A venogram is basically a radiograph of the foot after injecting a contrast substance into the digital veins. The configuration and the ramification of the vessels can be assessed according the zones of irrigation as shown in the pictures below.

abnormal venogram vs normal

After putting together the clinical signs and radiologic changes, the veterinarian-farrier team can provide a prognosis and a treatment plan for the horse.

Basic review of laminitis: Part II – treatment plan

Laminitis is a medical emergency and should the treated as such. It is very important for the veterinarian to establish a stabilization plan as soon as possible. As with any disease, the earlier the treatment starts, the better the prognosis and outcome. Unfortunately no one has found the complete cure to laminitis, but many horses do recover well from this painful disease if prompt and proper care is given. Many will return to athletic function and others can achieve to have a comfortable life and be pasture sound.

It is important to understand that the first signs of laminitis can vary from a subtle lameness to the typical laminitis stand as in picture 1. There is controversy on how to treat a horse in the early stages of the disease. There is usually an inciting incident that needs to be eliminated. Some of the more common causes of laminitis are obesity, insulin resistance (very common in Paso Finos), toxemia ( from pneumonia, colic, placental retention etc), trauma to the feet, severe non weight bearing of another leg (support limb laminitis) and more

Then medical treatment will be initiated towards decreasing inflammation, managing pain and treating the inciting cause. Because there is no proven cure to laminitis, there are many different options for intravenous and oral therapies that the veterinarian can choose from. Foot support and good biomechanics are crucial at this stage and all thorough the treatment of the disease. In order to provide a specific biomechanical treatment for any horse the farrier and veterinarian will perform frequent radiographic exams and sometimes venograms (as shown in the pictures). This will help identify were the coffin bone is located in relationship to the hoof capsule, therefore allowing correct shoe placement. It is extremely difficult and sometimes impossible to provide the necessary support to the feet without radiographic guidance.

A good farrier-veterinarian relationship will provide the best combination of pain management and mechanical support to the horse, therefore achieving the most comfortable solution for the patient.

Sometimes we perform venograms in order to evaluate the blood flow of the foot (picture 7). A venogram is a valuable tool in order to provide prognosis and evaluate the progression of treatment.

Furthermore, the veterinarian and farrier might decide to perform different techniques in order to re establish bonny alignment. This procedures are directed at relieving the pressure from the tendon that attaches to the coffin bone (deep digital flexor tendon). These vary from cutting the tendon (tenotomy) to inject relaxing medications into the muscle of that tendon (ie botox).

In summary, there is no cure to laminitis but if detected and treated early in the disease process, the chance of recovery is significantly higher. Pain management, correct biomechanics and proper support are one of the most important treatments for this disease. This is a disease that requires a great level of commitment from everybody involved in the life of that particular horse; owner, trainer, groom or care taker, farrier, veterinarian and others. It can take weeks to years from a horse that has suffered from laminitis to return to athletic function or even to be able to walk comfortably.